Hyaluronic acid is a linear polysaccharide (i.e., non-sulfated glycosaminoglycan) consisting of a repeated disaccharide unit of alternately bonded β-D-N-acetylglucoamine and β-D-glucuronic acid (i.e., (-4GlcUAβ1-3GlcNAcβ1-)n) which is a chief component of the extracellular matrix and is found, for example, in connective, epithelial and neural tissue. Natural hylauronic acid is highly biocompatible because of its lack of species and organ specificity and thus is often used as a biomaterial in tissue engineering and as a common ingredient in various dermal fillers.
Various chemically modified forms of hyaluronic acid (e.g., cross linked forms, ionically modified forms, esterified forms, etc.) have been synthesized to address a significant problem associated with natural hyaluronic acid which has poor in vivo stability due to rapid enzymatic degradation and hydrolysis. Currently, hyaluronic acid or cross linked versions thereof are used in various gel forms, for example as dermal fillers, adhesion barriers, etc.
However, substantial issues exist with the use of gels of hyaluronic acid or cross linked versions thereof. First, the force required to dispense gels of hyaluronic acid or cross linked versions thereof is non-linear which causes the initial “glob” that many physicians report when injecting hyaluronic acid or cross linked versions thereof. Second, precisely dispensing hyaluronic gels to specific locations is very difficult because such gels have little mechanical strength. Further, the gel will occupy the space of least resistance which makes its use in many applications (e.g., treatment of fine wrinkles) problematic.
Accordingly, what is needed are new physical forms of hyaluronic acid or cross linked versions thereof which can be dispensed uniformly to specific locations regardless of tissue resistance. Such new forms may have particular uses, for example, in aesthetic and surgical applications, drug delivery, wound therapy and wound dressing.